Week-by-Week Pregnancy Guide: Trimesters, Due Date and Milestones (2026)
Week-by-Week Pregnancy Guide: Trimesters, Due Date and Milestones A full-term pregnancy runs 40 weeks, split into 3 trimesters — first trimester weeks 1-13, second trimester weeks 14-27, and third trimester weeks 28-40 — and your due date equals the first day of your last menstrual period (LMP) plus 280 days. Weeks pregnant are counted as the number of days since your LMP divided by 7, which is why the count starts about two weeks before conception. Use the Due Date Calculator(/health/due-date-calculator) to turn your LMP into an exact estimated delivery date and trimester timeline. A common arithmetic slip repeats across pregnancy tracking: counting from the day of conception lands two weeks short of what a provider says. Here is the math that clears it up. A person whose LMP was March 1, 2026 is exactly 98 days along on June 7, 2026, and 98 divided by 7 is 14 —...
Pregnancy Week by Week: Complete Trimester Guide and Fetal Development
Pregnancy Week by Week: Complete Trimester Guide Every week of pregnancy brings new developments. From a cluster of cells smaller than a poppy seed to a fully-formed baby ready for the world, the transformation is nothing short of miraculous. Quick orientation: Pregnancy lasts 40 weeks and is divided into three trimesters. The first trimester (weeks 1-13) is when all major organs form. The second trimester (weeks 14-27) is when baby grows rapidly and you start feeling movement. The third trimester (weeks 28-40) is when baby gains weight and prepares for birth. Many parents check what's happening week by week obsessively -- first flutters commonly show up around week 19, the anatomy scan lands at week 20, and OBs typically recommend starting kick counts at week 28. A baby might arrive anywhere from 37 to 42 weeks, with 40 weeks and 3 days being a common full-term example. That week-by-week tracking...